1. Technical Field
The present invention relates to metal alloys used to make compression-spring mountings for stones used in jewelry and art objects. In addition, the invention relates to a method of forming heat-treatable metal compression-spring gemstone mountings.
2. Background Art
It is known in the jewelry art how to make prong-settings settings for precious and semi-precious stones. It is also known how to set such gemstones by raising metal around a stone to secure it in position, such as in bead-setting or bezel-setting.
It is also known in the jewelry-making art that the hardness and strength of alloys are increased by cold deformation. That is, it is known how to work-harden gold and platinum alloys by various forging processes to increase yield strength so as to create spring pressure. This spring pressure can be used to mount and center stones in rings, pendants, bracelets, etc. The pressure needed to hold the stone securely in place is supplied by the springiness inherent in the structure of the worked precious metal jewelry piece itself.
It is also known to those interested in the metallurgy of precious metals that many gold alloys and certain platinum alloys can be age-hardened by heat treatments to increase their hardness and yield strength, sometimes even more than is possible through cold working.
Conventional compression-spring gemstone mounting techniques have certain advantages over the more traditional prong settings because:
Often, more of the surface area of the girdle (peripheral edge) of the gemstone is held by the compression-spring mounting.
When struck with unusual force, a prong-mounted stone can shift and loosen when the prongs bend, but a compression-spring-set stone is held securely in its seat by spring pressure.
Besides the advantageous mechanical properties of compression-spring-set stones, this type of mounting exposes the stone to more light, thereby better bringing out the reflections and colors that are often hidden by prongs.
On the other hand, the work-hardening process for manufacturing compression-spring settings limits many of the possibilities for the design of jewelry or art objects. For example:
It is risky to bend spring-hard alloys to make adjustments because the metal is susceptible to fracturing without prior annealing. And, if the alloys are brought to annealing temperatures after they have been work-hardened, they will lose their hardness and become malleable. The stone will no longer be held by spring power, and the piece would be ruined.
The hardness and strength of the alloys are increased by cold deformation. The piece must be forged to shape to make it hard, like when a coin is struck, or when a ring is pounded on a mandrel with a hammer, etc. The spring power is arrived at with difficulty by working and shaping the piece, sometimes necessitating expensive presses and dies.
Standard jewelry soldering techniques cannot be applied to work-hardened compression-spring jewelry, because soldering temperatures anneal the alloy. Repairs requiring heat cannot be done without costing the metal its spring power. Jewelry designs utilizing compression-spring-set mountings therefore tend to be quite limited.
Accordingly, it is an object of the present invention to provide a method for forming metal compression-spring gemstone mountings having the advantages and being free of the drawbacks referred to above that are inherent in prior art methods for making compression-spring mountings.
Another object is to provide new and useful metal compression-spring gemstone mountings having the advantages and being free of the drawbacks referred to above that are inherent in prior art compression-spring mountings.
These and other objects of the invention as well as the advantages thereof can be had by reference to the following description, drawings and claims.